There´s any “problem” if i do litle stretch sessions some hours after speed work ( 1 or 2 sessions 20 minutes each at night ?
No. Static stretching is great after the cooldown. It would help alot if you stretched a few times throughout the day. Besides improving ROM it gets the muscle back to resting length which helps recovery.
Med ball rotations with stretching also has some benefit after speed/powerlifts.
Yes Quik, you´re right on this.
Yesterday i got very sore after speed work and then, at night, after shower, i did 30 minutes of static strech, very easy, very low, just working over the pain, man, it was very very good.
Today, o woke-up almost non sore, a thing that never happened before, without stretch.
Tks again !! 
great advice and it is proven that it does reduce DOMS but, does it not also run the risk of injury next time we train due to micro tears turning to major tears. I know the protein synthesis and how we recover plays a big role but sometimes that is impractical for some athletes. Any thoughts on this one?
Do not stretch to the point of pain. Static stretching should be be painful, if it is you are causing microtrauma or worsening the microtrauma caused from the workout and yes you are correct in saying you would be more susceptible to injury.